Abstract: Energy use in buildings is closely linked to their design (form, orientation and building materials), operational and space utilization characteristics and the behaviour of their occupants. Due to demand for sustainability, more passive buildings will be built in Egypt. This study evaluates the energy performance in a newly designed office building in Egypt. In this building, energy efficiency aspects were considered during the design. The evaluation is done using two different tools - Portfolio Manager (PM) and Target Finder (TF) - related to ENERGY STAR (ES) using the Energy Use Intensities (EUI). The only difference is that PM needs at least 12 consecutive months of metered utility bills to perform the evaluation calculations, while TF needs an estimated annual energy use for each type of energy consumed in the building. Energy consumption was determined by two ways: simulation and calculation. DesignBuilder (DB) has been used in the current study to simulate the building energy use for a whole year considering building design, building materials, optimization of thermal comfort, lighting, weather data and activity in the case study building. In addition, calculations for annual energy use were done using the data sheets with each energy consuming system utilized in the building based on operating hours of each. The ES scores for both simulation and calculation results were obtained. The main conclusions were that ES can be used to evaluate energy performance of office buildings in Egypt. Moreover, the results showed that the Egyptian office buildings can compete with the USA office buildings in applying energy efficiency strategies. Results of the optimizations showed significant reduction in terms of energy consumption. Finally, the simulation results showed the relative effect of the applied design, shading, orientation and the energy efficient lighting and HVAC systems on the annual energy consumption and ES score.